You're older than you've ever been and now you're even older, unless you're one of the lucky mice participating in a recent study that's partially reversed age-related degeneration, resulting in stronger, sharper brains and larger, more virile testicles.

It's a fact of life: Human's grow old. As we grow old our bodies begin to deteriorate. We lose the ability to procreate, our bodies get weaker, and our minds just aren't as sharp as they once were. It's inevitable.

Or is it?

Researchers led by Harvard Medical School professor of genetics Ronald A. DePinho at the Dana-Farber Cancer Institute are on the verge of publishing the results of a study that has partially turned back the hands of time in lab mice by engineering them with a controllable telomerase gene.

The telomerase enzyme is responsible for creating telomeres, which are caps that protect the ends of chromosomes from deteriorating. As human beings age, the level of telomerase enzyme in our bodies decreases. Without telomerase enzyme the protective caps deteriorate, which may be responsible for the tissue degradation and functional decline in the elderly.

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What the Harvard researches did was create mice with a controllable telomerase gene, which resulted in a batch of prematurely aged rodents. Their short, dysfunctional telomeres resulted in the sort of muscle and brain deterioration often seen in the elderly, as well as humans with premature aging disorders.

Rather than supply the rodents with supplemental telomerase, the scientists devised a way to switch on the animals' own dormant telomerase gene, known as TERT. They engineered the endogenous TERT gene to encode a fusion protein of TERT and the estrogen receptor. This fusion protein would only become activated with a special form of estrogen. With this setup, scientists could give the mice an estrogen-like drug at any time to stimulate the TERT-estrogen receptor fusion protein and make it active to maintain telomeres.

One group of mice had a time-release estrogen pill implanted under their skin. The other did not.

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After four weeks, the estrogen-treated mice showed amazing rejuvenation. The telomerase gene was working anew, creating healthy-sized telomeres. Tissue that was degenerating weeks before was now growing once more. The spleen and brain showed increased size. The animals regained their sense of smell, lost due to premature aging. Their brains began to produce new neurons. And yes, the testes were more powerful than ever.

"One of the most amazing changes was in the animals' testes, which were essentially barren as aging caused the death and elimination of sperm cells," recounted DePinho. "When we restored telomerase, the testes produced new sperm cells, and the animals' fecundity was improved - their mates gave birth to larger litters."

The animals did not live longer than their untreated counterparts, but it certainly sounds like they lived better.

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So what does this all mean to humans? The possibility of effectively reversing age-related diseases could change the way the world ages. The rest home industry could suffer and Wal-Mart might run out of greeters, but that's a small price to pay for a more graceful aging process, and who doesn't want more powerful testes?